1. Field of the Invention
The present invention relates to a device and a method of using the device for radio-frequency power coupling, particularly a power combiner and/or divider, comprising a box shaped casing as an outside conductor, connectors for input and output of RF-power, which are electrically connected to at least one center conductor.
2. Description of the Related Art
Devices for radio-frequency (RF) power coupling are power dividers and power combiners. Power dividers are used to divide RF power from single RF generators to multiple recipients. Power combiners are used to combine RF power from multiple sources to feed a single recipient with additional power. Recipients receiving RF power are, for example, loads or antennas. Most devices used as power divider or power combiner also work reciprocally, i.e. they can be used both as a divider and as a combiner. In the following, the use of the wording divider includes the use of a combiner and the use of the wording combiner includes the use of a divider. The main parameters for combiner/divider design in terms of RF power handling are heat and breakdown voltage. Requirements in use are the transmission of RF power with low insertion and return loss. Further requirements are compactness, easy assembly and cost effective, easy manufacturing.
There are two main types of conventional power combiners/dividers, e.g., based on printed circuit boards (PCB) or coaxial based combiners/dividers. PCB based combiners/dividers are mainly used in low power applications. Low power in this context is in the range of a couple of kilowatts in continuous wave regime to approximately ten kilowatts in pulsed mode use. PCB based devices are quite compact but are not for use in high power applications. Coaxial based combiners/dividers are usable for low power applications and for extremely high power levels, particularly up to hundreds of kilowatt. A disadvantage of coaxial based combiners/dividers is the lack of compactness, i.e., high volume respectively size.
A conventional combiner, e.g., as described in U.S. Pat. No. 4,459,568, is an air-stripe coupler. Here, power propagates in the gap between two strip lines. The device contains PCB, which does not enable high voltage usage. US 2012/0029327 discloses a conventional power combiner/divider that permits high power signals. This conventional power combiner/divider is relatively large in size and is not compact, and due to its cylindrical shape it cannot be used in racks. There is excessive empty space within the structure of the power combiner/divider.
U.S. Pat. No. 5,111,166 describes an electrical length equalization system for multiple inputs with inter alia power combining applications. Due to its PCB basing, this system can only be used in low power applications. Further, the handling and manufacturing of the system is not easy. The assembly comprises a complicated structure.
Described conventional devices, such as power combiner/divider with a PCB, cannot be used for high power applications due to high losses particularly producing high amounts of waste heat. The heat and high voltage can lead to irreversible damage of the devices. Devices for high power applications are not compact and have high insertion losses, leading to low efficiency.